This invention relates generally to devices for filtering and separating liquids. More particularly, the present invention relates to fuel filters for removing foreign particles and separating water from fuel in the fuel supply systems of an internal combustion engine.
Fuel filters commonly employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. The disposable cartridge is conventionally secured to the filter assembly base by a retaining or locking mechanism, which is releasable to allow for the removal of the cartridge for replacement purposes. There are numerous conventional fuel filter cartridge base retention systems. Many of such retention systems become exceedingly troublesome to use or even fail over time due to the harsh environment of the fuel filter assembly.
In U.S. Pat. No. 5,017,285, which is assigned to the assignee of the present invention, one disclosed inverted fuel filter assembly employs a base which fixedly mounts to the vehicle. A disposable filter cartridge is suspended directly below the filter base. The cartridge is retained to the base by a threaded collar. The collar includes a ramp which retentively engages against a circumferential roll seam structure at the periphery of the cartridge housing. The collar threads to the base, and the cartridge is replaced by loosening the threaded collar and dismounting the filter cartridge.
In U.S. patent application Ser. No. 7/466,693 filed on Aug. 16, 1991, which application is assigned to the assignee of the present invention, a disclosed fuel filter assembly employs a retainer collar which locks the disposable cartridge to the base. The base has an inverted cup-like receiving skirt. A pair of spiral ramps extend at the exterior of the skirt. Stops are angularly spaced from an upper end of the ramp to define detentive slots. The disposable cartridge which houses one or more filter elements is partially receivable by the base skirt. The cartridge has a peripheral engagement flange. The retainer collar has a shoulder which is engageable against the flange and an integral inner spiral follower which terminates in a catch. A spring in the form of a spring washer which has two alternating sets of spring leaves is disposed between the base and the cartridge. One set of the leaves is engageable against the cartridge and the other is engageable against the base. The spring washer is retained to the base by means of a retainer ring. Each follower rides the base ramp until the catch engages the stop and is positively captured in the slot under the bias of the spring.